This proposal is for continuation of a program for producing appropriately purified and carefully assayed preparations of erythropoietin for distributing them to qualified investigators for use in research, and for continuing to investigate methods for more efficient isolation, purification and assay of human erythropoietin. The goal of this project is to ensure the continued availability to investigators of a variety of erythropoietin preparations for uses including the following: Clinical tests of erythropoietin and preparatory animal expermentation, study of the biochemical and immunological nature - cellular sites of action - mechanism of action of human erythropoietin - development of new purification procedures and assay methods. A laboratory shall be maintained to receive crude preparations of human erythropoietin from the urine of anemic individuals as collected from various populations. This material will be refined and fractionated by biochemical procedures established in this laboratory. Materials will be carefully assayed both in vivo and in vitro. Stocks will be kept on inventory and dispensed to qualified investigators according to the directions of the NHLI based on the recommendations of an advisory committee.